Electrical and conductive properties of epoxy based conductive ink filled with graphite and carbon black

This study addresses the global rise in electronic waste by developing an environmentally friendly, carbon-based conductive ink free of metal content. The objective was to formulate a conductive ink using epoxy resin as a binder and Carbon Black (CB) and Graphite (GP) as conductive fillers, investigating both their individual and combined effects to optimize electrical conductivity and adhesion properties. A series of ink formulations with varying CB and GP concentrations (0–25%) and combinations of CB-GP conductive ink in varied ratios were prepared and screenprinted onto polyethylene terephthalate (PET) substrates. Key characterization techniques included X-ray diffraction (XRD), UV-Visible spectroscopy, Fouriertransform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FESEM) to assess material structure, filler interaction, and dispersion quality. The findings revealed that while individual fillers provided moderate conductivity, the synergistic combination of CB and GP significantly enhanced performance. The epoxy composite with 20% CB achieved a conductivity of approximately 3.66 × 10⁻³ S/m, and 15% GP alone reached 3.77 × 10⁻³ S/m, as measured by Electrochemical Impedance Spectroscopy (EIS). However, the optimized ink at a CB:GP ratio of 1:2 exhibited a peak conductivity of 3.87 × 10⁻³ S/m, confirmed through EIS, with consistent results from two-point and four-point probe measurements. FESEM imaging showed a uniform dispersion of CB and GP particles forming a dense, interconnected conductive network within the epoxy matrix, facilitating efficient electron transport pathways. FTIR analyses confirmed the physical integration of fillers within the epoxy matrix, indicating good compatibility between components and contributing to the network’s stability. Adhesion testing demonstrated excellent inksubstrate compatibility. The optimized 1:2 CB-GP ink showed a wettability contact angle of 36.8°, indicating good surface affinity, while pull-off tests recorded a strength of 0.41 MPa, confirming robust mechanical interlocking. Cross-cut adhesion tests further validated the coating’s integrity without delamination or fragmentation. Theoretically, this study advances understanding of the synergistic role of filler morphology and dispersion in polymer-based conductive systems. Practically, it presents a sustainable, cost-effective conductive ink suitable for printed electronics applications such as RFID tags, sensors, flexible displays, and electrical circuits. This work offers a promising approach for e-waste upcycling through innovative conductive ink formulation.